Many technologies, based on different physics principles, have been developed to perform a magnetic field measurement using a miniature sensor. Examples in particular include Hall effect sensors, GMR (giant magnetoresistance) sensors, AMR (anisotropic magnetoresistance) sensors, fluxgate or magnetometric sensors, Lorentz force sensors, or magnetic material sensors.
One of the problems frequently encountered concerns the production of a sensor able to perform a magnetic field measurement along several axes. Sensors measuring the components of a magnetic field along two axes located in the plane of the sensor have already been made. But when one wishes also to measure the vertical component of the magnetic field (component perpendicular to the plane of the sensor), the production of such a sensor becomes much more complex, in particular if one wishes for this sensor also to measure magnetic components of the magnetic field located in the plane of the sensor.
Moreover, certain types of sensors are not adapted to perform certain magnetic field measurements. For example, to perform a measurement of the geomagnetic field, Hall effect sensors have resolutions much too low to precisely determine the direction of this magnetic field. GMR sensors have a hysteresis and perform a low-field non-linear measurement (less than about 100 μT) incompatible with a measurement of the geomagnetic field (equal to about 50 μT).
Other types of sensors also have substantial electricity consumption, such as AMR and fluxgate sensors for example, which can be a drawback, for example when these sensors are intended to be used in onboard applications.
Lorentz force sensors are quite large when one wishes to perform a precise measurement of a magnetic field such as the geomagnetic field. Furthermore, their operation in resonant mode requires substantial quality factors that can only be obtained through costly vacuum packaging.
Relative to Lorentz force sensors, hard magnetic material sensors do not require current for a force or torque to be created in the presence of a magnetic field, which represents an advantage in terms of electricity consumption. However, existing magnetic material sensors have other major drawbacks: detection according to only 1 or 2 axes, non-integrated sensor, excessive sensitivity to accelerations, or excessively low magnetic field detection sensitivity.